1. Field of the Invention
The invention relates to composite blow molded articles. More specifically, the invention relates to composite blow molded articles used in motor vehicles.
2. Description of the Related Art
There are several methods by which components found in the passenger compartment of a motor vehicle may be manufactured. The method of choice depends on cost and finish. One method of manufacturing such items as head rests, arms rests, instrument panels and the like is blow molding. Blow molding is the term which is generally used to describe a type of thermoplastic manufacturing process. A parison is a thermoplastic tube or bag which is heated and extruded through a die. A fluid, typically pressurized air, fills the parison and stretches it to a desired size. Wall thickness is determined by the die design but can be influenced by the air. The stretched parison is then placed on a mold to be shaped. Once the mold closes around the parison, the parison is pierced by a needle that blows air inside the pinched parison. This is the fluid medium that forms the shape of the skin to that of the mold. Once shaped and cooled, the skin (parison) can be filled or otherwise worked as desired.
U.S. Pat. No. 4,891,081, issued to Takahashi et al. on Jan. 2, 1990, discloses a method for producing a foamed resin molding having a skin and a foam cushion formed within that skin. While this method does not disclose the creation of an article using blow molding, it does disclose the use of inserts which are held in place by the skin to create an appearance of a composite skin. To do this, however, creases must be created in the skin wherein those creases extend over the outer surface of the insert. These creases cannot be made when blow molding. Further, the creases increase the thickness at the periphery of the insert which is an undesired effect.